package com.hmdp.service.impl;

import cn.hutool.core.util.BooleanUtil;
import cn.hutool.core.util.StrUtil;
import cn.hutool.json.JSONObject;
import cn.hutool.json.JSONUtil;
import com.baomidou.mybatisplus.extension.plugins.pagination.Page;
import com.hmdp.controller.ShopController;
import com.hmdp.dto.Result;
import com.hmdp.entity.Shop;
import com.hmdp.mapper.ShopMapper;
import com.hmdp.service.IShopService;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import com.hmdp.utils.CacheClient;
import com.hmdp.utils.RedisConstants;
import com.hmdp.utils.RedisData;

import com.hmdp.utils.SystemConstants;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.data.geo.Distance;
import org.springframework.data.geo.GeoResult;
import org.springframework.data.geo.GeoResults;
import org.springframework.data.redis.connection.RedisGeoCommands;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.data.redis.domain.geo.GeoReference;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;
import org.yaml.snakeyaml.events.Event;

import javax.annotation.Resource;

import java.sql.Time;
import java.time.LocalDateTime;
import java.util.*;
import java.util.concurrent.Executor;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;

import static com.hmdp.utils.RedisConstants.*;

/**
 * <p>
 *  服务实现类
 * </p>
 *
 * @author 虎哥
 * @since 2021-12-22
 */
@Service
public class ShopServiceImpl extends ServiceImpl<ShopMapper, Shop> implements IShopService {

    @Resource
    private StringRedisTemplate stringRedisTemplate;


    @Resource
    private CacheClient cacheClient;
    @Autowired
    private ShopController shopController;

    @Override
    public Result queryById(Long id) throws InterruptedException {
        //1.缓存穿透
        //Shop shop = queryWithPassThrough(id);//
        //采用打包redis的工具的方式，来进行缓存穿透
        /*Shop shop = cacheClient.queryWithPassThrough(
                CACHE_SHOP_KEY, id,Shop.class,id2 -> getById(id2),CACHE_SHOP_TTL, TimeUnit.MINUTES);
*/
        //2.互斥锁解决缓存击穿
        //Shop shop = queryWithMutex(id);

        //3.采用逻辑过期解决缓存击穿
        /*Shop shop = queryWithLogicalExpire(id);
        if (shop == null) {
            return Result.fail("店铺不存在！");
        }*/
        Shop shop = cacheClient.queryWithLogicalExpire(
                CACHE_SHOP_KEY, id,Shop.class,id2 -> getById(id2),CACHE_SHOP_TTL, TimeUnit.MINUTES);


        //7.返回
        return Result.ok(shop);

    }

    private static final ExecutorService CACHE_REBUILD_EXECUTOR = Executors.newFixedThreadPool(10);

    public Shop queryWithLogicalExpire(Long id){
        String  key = CACHE_SHOP_KEY + id;
        //1.从redis查询商铺缓存
        String shopJson = stringRedisTemplate.opsForValue().get(key);
        //2.判断是否存在
        if (StrUtil.isBlank(shopJson)) {
            return null;
        }

        //4. 命中，需要先把json反序列化为对象
        RedisData redisData = JSONUtil.toBean(shopJson, RedisData.class);
        JSONObject data = (JSONObject)redisData.getData();
        Shop shop = JSONUtil.toBean(data, Shop.class);
        LocalDateTime expireTime = redisData.getExpireTime();
        //5.判断是否过期
        if (expireTime.isAfter(LocalDateTime.now())) {
            //5.1 未过期，直接返回店铺信息
            return shop;
        }


        //5.2 已过期，需要缓存重建

        //6. 缓存重建

        //6.1 获取互斥锁
        //lockshop
        String lockKey = LOCK_SHOP_KEY + id;
        Boolean isLock = tryLock(lockKey);
        //6.2 判断是否获取锁成功
        if (isLock) {
            // TODO 6.3 成功，开启独立线程，实现缓存重建
            CACHE_REBUILD_EXECUTOR.submit(() -> {
                //重建缓存
                try {
                    this.saveShop2Redis(id,20L);

                } catch (Exception e) {
                    throw new RuntimeException(e);
                } finally {
                    //释放锁
                    unLock(lockKey);
                }

            });
        }
        //6.4.返回过期的店铺信息
        return shop;
    }


    public Shop queryWithMutex(Long id) throws InterruptedException {
        String  key = CACHE_SHOP_KEY + id;
        //1.从redis查询商铺缓存
        String shopJson = stringRedisTemplate.opsForValue().get(key);
        //2.判断是否存在
        if (!StrUtil.isBlank(shopJson)) {
            //3.存在，直接返回
            Shop shop = JSONUtil.toBean(shopJson, Shop.class);
            return shop;
        }

        //判断命中的是否是空值
        //!StrUtil.isBlank(shopJson)对于true的要求很高，所以需要二次判断是否为null
        if (shopJson != null) {
            //返回一个错误信息
            return null;
        }


        //4.实现缓存重建
        //4.1 获取互斥锁
        String lockkey = "lock:shop:" + id;
        Shop shop = null;
        try {
            boolean isLock = tryLock(lockkey);
            //4.2 判断是否获取成功
            if(!isLock){
                //4.3 失败，则休眠并重试
                Thread.sleep(50);//这个方法可能抛出 InterruptedException
                //递归来一次
                return queryWithMutex(id);
            }

            //4.4 成功，根据id查询数据库
            shop = getById(id);
            //模拟重建的延时
            Thread.sleep(200);

            //5.不存在，返回错误         //4.不存在，根据iD查询数据库
            if (shop == null) {
                //将空值写入redis  //返回错误信息
                stringRedisTemplate.opsForValue().set(key,"",CACHE_NULL_TTL,TimeUnit.MINUTES);

                return null;
            }

            //6.存在，写入redis
            //设置超时的时间
            stringRedisTemplate.opsForValue().set(key, JSONUtil.toJsonStr(shop),
                    CACHE_SHOP_TTL, TimeUnit.MINUTES);
        } catch (InterruptedException e) {
            throw new RuntimeException(e);
        } finally {
            //7. 释放互斥锁
            unLock(lockkey);
        }
        //8. 返回
        return shop;
    }

    public Shop queryWithPassThrough(Long id){
        String  key = CACHE_SHOP_KEY + id;
        //1.从redis查询商铺缓存
        String shopJson = stringRedisTemplate.opsForValue().get(key);
        //2.判断是否存在
        if (!StrUtil.isBlank(shopJson)) {
            //3.存在，直接返回
            Shop shop = JSONUtil.toBean(shopJson, Shop.class);
            return shop;
        }

        //判断命中的是否是空值
        //!StrUtil.isBlank(shopJson)对于true的要求很高，所以需要二次判断是否为null
        if (shopJson != null) {
            //返回一个错误信息
            return null;
        }

        //4.不存在，根据iD查询数据库
        Shop shop = getById(id);
        //5.不存在，返回错误
        if (shop == null) {
            //将空值写入redis  //返回错误信息
            stringRedisTemplate.opsForValue().set(key,"",CACHE_NULL_TTL,TimeUnit.MINUTES);

            return null;
        }

        //6.存在，写入redis
        //设置超时的时间
        stringRedisTemplate.opsForValue().set(key, JSONUtil.toJsonStr(shop),
                CACHE_SHOP_TTL, TimeUnit.MINUTES);
        //7.返回

        return shop;
    }


    private boolean tryLock(String key){
        //只有当 key 不存在时，才设置值;;单位是秒，即 10 秒
        Boolean flag = stringRedisTemplate.opsForValue().setIfAbsent(key, "1", 10, TimeUnit.SECONDS);
        //flag有可能不存在
        return BooleanUtil.isTrue(flag);
    }

    private void unLock(String key){
        stringRedisTemplate.delete(key);
    }

    public void saveShop2Redis(Long id,Long expireSeconds) throws InterruptedException {
        // 1.查询店铺数据
        Shop shop = getById(id);

        Thread.sleep(200);

        // 2.封装逻辑过期时间
        RedisData redisData = new RedisData();
        redisData.setData(shop);
        redisData.setExpireTime(LocalDateTime.now().plusSeconds(expireSeconds));
        //3.写入Redis
        stringRedisTemplate.opsForValue().set(CACHE_SHOP_KEY+id,JSONUtil.toJsonStr(redisData));

    }

    @Override
    @Transactional//为了确保：只有数据库成功更新了，缓存才会被删除。
    //保证方法中的数据库操作具有原子性（要么全部成功，要么全部失败），以防止数据不一致的问题。
    public Result update(Shop shop) {
        Long id = shop.getId();
        if (id == null) {
            return Result.fail("店铺id不能为空");
        }

        //1.更新数据库
        updateById(shop);
        //2.删除缓存;
        stringRedisTemplate.delete(CACHE_SHOP_KEY + id);
        return Result.ok();
    }

    @Override
    public Result queryShopByType(Integer typeId, Integer current, Double x, Double y) {
        // 判断是否需要根据坐标查询
        if(x == null || y == null){
            // 根据类型分页查询
            Page<Shop> page = query()
                    .eq("type_id", typeId)
                    .page(new Page<>(current, SystemConstants.DEFAULT_PAGE_SIZE));
            // 返回数据
            return Result.ok(page.getRecords());
        }
        // 计算分页参数
        int from = (current - 1) * SystemConstants.DEFAULT_PAGE_SIZE;
        int end = current * SystemConstants.DEFAULT_PAGE_SIZE;

        // 查询 Redis，按照距离排序、分页。
        GeoResults<RedisGeoCommands.GeoLocation<String>> search = stringRedisTemplate.opsForGeo().
                search(RedisConstants.SHOP_GEO_KEY + typeId,
                        GeoReference.fromCoordinate(x, y),
                        new Distance(5000),
                        RedisGeoCommands.GeoSearchCommandArgs.newGeoSearchArgs().includeDistance().limit(end));

        if(search == null){
            return Result.ok(Collections.emptyList());
        }

        // 查询 Redis，按照距离排序、分页
        List<GeoResult<RedisGeoCommands.GeoLocation<String>>> content = search.getContent();
        if(from >= content.size()){
            //没有下一页了，结束
            return Result.ok(Collections.emptyList());
        }

        List<Long> ids = new ArrayList<>(content.size());
        Map<String, Distance> distanceMap = new HashMap<>(content.size());
        // 截取 from ~ end 的部分
        content.stream().skip(from).forEach(result -> {
            // 获取店铺 id
            String shopIdStr = result.getContent().getName();
            ids.add(Long.valueOf(shopIdStr));
            // 获取距离
            Distance distance = result.getDistance();
            distanceMap.put(shopIdStr, distance);
        });
        String join = StrUtil.join(",", ids);
        // 根据 id 查询 shop
        List<Shop> shopList = query().in("id", ids).last("order by field(" + join + ")").list();

        for (Shop shop : shopList) {
            shop.setDistance(distanceMap.get(shop.getId().toString()).getValue());
        }

        return Result.ok(shopList);


    }
}
